摘要:

AbstractThe morphology of parafollicular (C) cells in the thyroid gland of the woodchuck,Marmota monax, was studied during the four seasons of the year. The spring C cells are characterized by a large Golgi zone, rough‐surfaced endoplasmic reticulum, free ribosomes and relatively few dense granules. In the summer these cells appear to be larger and many are packed with dense granules. Fall cells exhibit morphological characteristics suggestive of intense synthetic activity, having rough‐surfaced endoplasmic reticulum in whorls or parallel arrangement, a large Golgi apparatus and few, to many granules, some of which are larger than those seen in the spring and summer C cells. In the winter, most of the C cells are packed with granules. The Golgi zone, when observed, is small and the rough‐surfaced endoplasmic reticulum is sparse. Many cell profiles exhibit apparent granule dissolution. These cyclic morphological findings are discussed along with previous studies of other hibernators and are correlated with the seasonal activities of the wood

ISSN:0003-276X    

DOI:10.1002/ar.1091890302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractThe differentiation of the mitral cell perikaryon in postnatal rat olfactory bulb was studied with the light and electron microscope. At birth the mitral cell was distinguishable and occupied a definitive position in the mitral cell layer. The cell contained a large oval nucleus surrounded by a thin rim of cytoplasm. Ribosomes, free and clustered, were scattered in the cell cytoplasm. Rough endoplasmic reticulum was relatively scarce. The Golgi complexes were made up of stacks of smooth‐surfaced cisternae and associated vesicles. In certain cases the Golgi complexes projected into cellular processes. Mitochondria were present in all regions of the cytoplasm and contained well developed cristae. At the end of the first week, the mitral cell had developed significantly in size, and the cytoplasm contained well‐developed rough endoplasmic reticulum. The Golgi complexes were made up of several stacks of smooth‐surfaced cisternae with the association of vesicles and electron dense bodies. The apical dendrites o mitral cells at this periiod had increased significantly in length. Subsequently, during the second and third week, the rough endoplasmic reticulum and Golgi complexes became well developed. Associated with the Golgi complexes were electron dense lysosomal bodies. At three weeks and in older cells it was observed that dense lysosomal bodies. At three weeks and in older cells it was observed that dense lipofuschin granules increased significantly. It is suggested that the mitral cell matures and differentiates earlier than cells in the cerebral c

ISSN:0003-276X    

DOI:10.1002/ar.1091890303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA scanning electron microscopic (SEM) study of palatal mucosa maintained in organ culture (50% O2‐Eagle's MEM w/o serum) from 12 to 360 hours is presented. The morphological changes occurring in the explants during culture are illustrated and the findings are compared with those observed using transmission electron microscopy and light microscopy. The results confirm that cellular fine structure in epithelium and connective tissue is more easily visualized when SEM is employed following in vitro maintenance of explants as opposed to examination of fresh uncultured biopsies. The in vitro system used would appear to be applicable to studies designed to investigate the effect of various substances on cell proliferation and cell interaction

ISSN:0003-276X    

DOI:10.1002/ar.1091890304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA method was developed to alter surgically the bursa of the bitch to allow sequential observation of the ovary by means of laparoscopy. Adult anesthetized female dogs of three breeds underwent laparoscopic examinations in which each natural bursa slit was lengthened 1.0‐1.5 cm using laparoscopic hook scissors in conjunction with electrocautery. The ovary could be effectively and repeatedly exposed for laparoscopic viewing through the lengthened bursa slit. Neither Laparoscopic surgery nor frequent routine laparoscopic examinations of the reproductive organs had an effect on subsequent ovarian activity. All dogs subjected to the laparoscopic ovarian exposure technique exhibited estrus behavior, follicle development, ovulation and corpus luteum formation.Preovulatory follicular development was detected as early as 11 days before ovulation with the most rapid follicular maturation occurring two to three days before ovulation. Follicular collapse and extensive hemorrhage at the rupture site during ovulation did not occur. Release of the cumulus mass from a vesicular follicle was observed in one bitch. The cumulative mass adhered to the follicular wall for an indefinite time following ovulation.The structural size of the bitch corpus luteum was maximal four to eight days following ovulation. Corpora lutea remained visible on the ovarian surface for 16 weeks. No differences in cyclic ovarian morphology were observed among the three breeds of dogs studie

ISSN:0003-276X    

DOI:10.1002/ar.1091890305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractIncisor and molar tooth germs of albino rats sacrificed at the eighteenth and twentieth days in utero and one to seven days after birth were studied with light and electron microscopy. Observations of the various stages of tooth development in molars established that intramitochondrial granules in odontoblasts were comparable to the intramitochondrial granules of other hard tissue cells. These electron‐dense deposits appeared in mitochondria in an appreciable number only when odontoblasts become engaged in dentin mineralization. When dentin mineralization was advanced the odontoblast mitochondria appeared devoid of these deposits. Mesenchymal cells and preodontoblasts of the pulp were not involved in this activit

ISSN:0003-276X    

DOI:10.1002/ar.1091890306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractVentral pharyngeal outpocketings and ultimobranchial out‐pocketings from the 14‐day‐old fetus of the Fischer rat were isolated before they fused to form thyroid glands. The outpocketings were implanted into different kidney capsules of adult male Fischer rats, and were allowed to grow for several months. Transplants were then excised and examined by electron microscopy. The ultimobranchial outpocketing gave rise to two types of follicles. One contained ciliated cells, cells with an abundant agranular reticulum, U cells with basal hemidesmosomes, and two types of cells with secretory vesicles. The other contained C cells separated from the follicular lumen by a single flat fiber‐con‐taining cell. The ventral outpocketing formed typical thyroid epithelium making up the usual thyroid follicles differing from follicles in the thyroid in situ by the absence of C cells. These follicles were functional as determined by autoradio‐graphic studies with125I but differed from thyroid follicles in situ with respect to size distribution. The results suggest that (1) in the adult thyroid gland the C cell in the usual follicle is an ultimobranchial contribution and (2) the so‐called ultimobranchial follicle is ultimobranchial in origin but that the typical thyroid epithelium in mixed follicles of U cells and typical thyroid epithelium is a ventral contribution. The reason for the absence in the thyroid gland in situ of the variety of other cell types observed in ultimobranchial transplan

ISSN:0003-276X    

DOI:10.1002/ar.1091890307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractIn an attempt to localize the site of remodelling of collagen in the periodontal ligament of the continuously erupting mouse incisor a radioautographic and stereologic investigation was undertaken. Grain distributions in radioautographs for light microscopy were studied at various time intervals after administration of [3H]‐proline. The distribution of rough endoplasmic reticulum cisternae in fibroblasts and the incidence of collagen phagocytosis across the ligament were studied by means of stereologic methods at the electron microscopic level.No significant differences were found in half lives of [3H]‐labelled substances among the various regions across the ligament. Roughendoplasmic reticulum cisternae within fibroblasts were distributed more or less uniformly throughout the entire width of the ligament. Analysis of the distribution of collagen phago‐cytosis, however, revealed that in the midregion of the ligament the amount of phagocytosed collagen was approximately four times as high as in the area adjcent to the tooth and about nine times as high as in the alveolar compartment.It is concluded that synthesis and turnover of total protein occurs throughout the periodontal ligament but that remodelling of collagen predominantly takes place in an intermediate area of the lig

ISSN:0003-276X    

DOI:10.1002/ar.1091890308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA study of the development of hemopoiesis in the Mongolian gerbil(Meriones unguiculatus)was conducted in order to determine the temporal sequence, the organs involved and the cytology of blood cell formation in this species. Hemopoiesis in the intrauterine life of the gerbil can be divided into four phases based on the site of blood cell formation: (1) the vitelline phase, (2) the hepatic phase, including thymic histogenesis, (3) the splenic phase and (4) the medullary phase, with the development of secondary lymphoid tissues. At the onset of each of these phases a blast‐like cell was identifiable in each hemopoietic organ which, because of its morphology and its presumed multipo‐tentiality was classified as a “lymphoid cell.” In the yolk sac phase (gestational day 12) two generations of erythrocytes, a primitive and a definitive, are formed. The liver is by day 15 erythropoietic and megakaryopoietic, but later, a few gran‐ulocytes are also found in its extravascular compartment. The thymus is exclusively lymphopoietic from the appearance of its earliest cells on day 15. Splenic hemopoiesis is initiated with the presence of lymphoid cells (day 20) followed later by the appearance of morphologically identifiable blood cell lines. Early normoblastic and granulocytic activity begins in the marrow cavities on day 23, though the marrow is not considered to be a source of circulating blood cells during fetal life. Lymph node histogenesis occurs during the last four days of gestation, first in the cervical region and then in other parts of the body. The finding of undifferentiated lymphoid cells in all organs at the initiation of hemopoiesis and in the peripheral blood throughout gestation is discussed in light of the migratory theory of he

ISSN:0003-276X    

DOI:10.1002/ar.1091890309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractMuscle spindles were sought in peri‐auricular muscles of several primate species (rhesus monkey, woolly monkey, and baboon). Transverse sections cut at 10 μ and stained primarily by a silver impregnation technique were examined using light microscopy. Spindles were identified on the basis of standard criteria. Posterior and/or superior auricular muscles of each species were found to contain spindles. At least some muscles innervated by facial nerve have classical spindles as component structur

ISSN:0003-276X    

DOI:10.1002/ar.1091890310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1091890311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY